Vertical master cylinder



Feb. 9, 1937. s. SCHNELL VERTICAL MASTER CYLINDER Filed March 18, 1935{NVENTOR STEVE SCHNELL z K II III III J fi l||.|)

AT'T Y.

Patented Feb. 9, 1931 UNITED" STATES PATENT OFFICE ner ElectricCorporation, corporation of Delaware St. Louis, Mo., a

Application March is, 1935, Serial-No. 11,549 1 7 Claims. (01. Gil-54.6)

My invention relates to fluid braking apparatus and more particularly toa vertical master cylinder device for creating pressure in fluid brakeactuating system. I

One of the objects of my invention isto pro,-

duce an improved master cylinder device of the vertically positionedvtype which'is'simple in construction, economical to manufacture andassemble,' eflicient' in operation, and easy to in- .stall on a vehicle.p

Other objects will become apparent fro'nf'the following descriptiontaken in connection with the accompanying drawing in which Figure 1 is apartial cross sectional view of my improved master cylinder device, and2 is a top view thereof.

Referring to the drawing in detail, the vertically positioned cylinderI. is provided with a piston 2 which piston is normally maintained at 0the rear of the cylinder by a coil spring 3 interposed between thepiston head and the cylinder head 4, the latter being threaded in thecylinder for easy assembly and disassembly. Therear end of the cylinderis provided with an integral flange b which acts as a stop for thepiston when. it is in its normally retracted position under the actionof spring This stop may, if desired, be detachable instead of integralas shown. The piston is formed with an annular recess 6, therebyforming, with the cylinder wail, an annular fluid containing chamber,the purpose of which will be later apparent. The head of the piston hasformed therein a plurality of passages I for placing the annular recess6 in communication with the portion of the cylinder ahead of the piston.The rear of the piston cooperates with the cylinder to form guidingmeans during the reciprocation oi the piston. The piston is also shownas being provided with the usual rubber packingcup 8 adjacent the headof the piston, .such packing cup,

being maintained in contact with thepiston head bymeans of spring 8.

The exterior of the cylinder I has formed vi5 thereon an annular flange9 and a threaded portion ill adjacent and above the flange. Thereservoir casing Ii for the master cylinder device is provided in itsbottom with a'threaded opening I2 through which extends the upperportion of the cylinder I, into the reservoir casing II. The opening I2is strengthened by means of a.

boss I! and the threads thereon, together with the threads of theopening i2, cooperate with the threaded portion IQ of the cylinder tode: tachably connect the cylinder and the reservoir casing. Asuitablegasket It is interposed between the boss 13 andthe annular flange 9 onthe cylinder to efliciently seal the reservoir casing and cylindertogether.

The cylinder I is formed with an opening I! 5 commonly known as thecompensating port", this opening being positioned ahead of; the lip oithe packing cup. when the piston and'packing means of a groove l6 cutthrough the threads on the threaded portion iii of the cylinder. Theportion of the cylinder which extends into the reservoir casing hasformed therein an opening 15 ll for placing the annular recess 6 of thepiston in constant communication with the reservoir. The piston isformed with a piston rod receiving socket l8 which is in communicationwith the annular recess of the piston by the passage i The piston rod 20is adapted to'loosely abut the piston and extends through an enlargedopening in the top of the reservoir casing for connection with thebrakepedal 2| by means of a clevis 22. A suitable flexible dust excludingboot 25 23 surrounds the piston rod and has one end connected to theclevis and the other end clamped to a suitable annular flangesurrounding the piston rod opening in the top of the reservoir.Breathing means for the. boot and the reservoir 30 is formed in thepistonrod instead of in the boot wall and comprises a cross passage 26and a connecting longitudinal passage 31 extending to the atmosphere atthe outer end of the piston rod. By this construction the breatheropening 5 is well protected from foreign material because of itslocation directly beneath the pedal.

The brake pedal 2| is pivotally mountedupon .the shaft, which shaft ismounted upon support 25 or the vehicle by a bearing 26. The sun- 40 port25 is a portion of the frame of the vehicle I and is in the form of anangle iron having a top I flange2l adapted to carry and support themaster cylinder device. As shown in the drawing, the reservoir casinghas formed thereon a boss" 45 which fits up against flange-21 oi thesupport and is clamped thereto by a bolt 29. The reservoir casing isalso provided with a pair of trunnions 30 adapted to surround the shaft24 and to additionally support the master cylinder de- .50 vice fromflange. of the support by means of shaft 24. The brake pedal 2| isprovided with, a short extension 3 l carrying a set-screw 32 which isadapted to cooperate with a stop 33 on the top of the reservoir casing,thus providing adjustable 55 stop means for the brake pedal. Thereservoir casing is also shown as being provided with a filler openingclosed by means of a suitable plug 34.

In the. operation of my improved master cylinder device the lower end ofthe cylinder is connected to the wheel cylinders of the brakes (notshown) by conduits 35 and the entire system is filled with a suitableliquid, the air in the system being removed in a well-known manner. Whenthe pedal 2| is actuated, the piston rod 20 forces the piston '2downwardly, thereby cutting off the compensating port It and forcingfluid under pressure through conduits 35 to actuate the brakes. When thepedal is released, the spring 3 will move piston 2 to its normallyretracted position against the stop 5. If, for any reason, the pistonshould be returned more rapidly than fluid is returned to the cylinderfrom the brake applying cylinders, thereby tending to create asub-atmospheric pressure in the cylinder ahead of the piston, the fluidin the annular recess of the piston will flow through piston passages-1and around the lip of the cup to maintain the cylinder filled withliquid. Air is thus prevented from being drawn into the system during.re tractile movement of the piston, since, due to the position of thereservoir above the piston, liquid will always be maintained at' therear of the piston head because the annular recess 6 is at all times incommunication with the reservoir by way of opening l1. When the pistonassumes its retracted position the compensating port l5 will beuncovered and any excess liquid in the cylinder will be returned to thereservoir by way of groove l6.

An important feature of my invention is the position of the reservoirwith respect to the com-.

pensating port or opening l5. It is to be noted from the drawing thatthis port is below the bottom of the reservoir casing, thus thecompensating port and the groove connected thereto willalways be fedwith liquid as long as there is any liquid in the reservoir. In allother master cylinders of the vertical type of which I have knowledge, acertain amount of liquid may be in the reservoir but at the sametime'the compensating port, due to its position, will be dry, thusallowing air, to enter the system and-thereby decrease its efliciency..The positioning of the reservoir as shown, and the provision of passage19 in the piston, also insures that liquid will be' maintained in thepiston rod receiving socket of the piston for lubricating purposes.Another important feature of my invention is that by posi-' tioning thereservoir as shown, a considerable saving in reservoir material isaccomplished.

' Also, since the master cylinder device is composed of only two parts,they are readily assembled and disassembled by merely screwing themtogether or unscrewing them. I There is also no problem present in thisdevice to insure that clamp the reservoir to flange 21 by means of. bolt29 to produce very rigid installation. The entire device is compact,requiring only a very small over-all space.

- with an annular flange and a threaded portion intermediate its ends,the upper end of said cylinder extending into the reservoir casing andthe threaded portion cooperating with the threaded reservoir opening toclamp the annular flange in fluid-tight engagement with the bottom ofthe reservoir casing, a piston reciprocable in the cylinder, saidcylinder being provided with an openthe rear of the cylinder and thepiston rod be sealed to prevent leakage of liquid from the cylinder andthe reservoir casing. The level of the liquid in the reservoir is at alltimes I the piston rod opening in the top wall of reservoir casing.

The cylinder is preferably of cast construction, while the reservoir maybe either made of cast material or of pressed steel as desired.

From the foregoing description it will be readily seen that the deviceis very quickly installed in a vehicle. All that is necessary is toslide the pedal and the trunnions 30 on to the shaft 24 and then the ingpositioned below'the bottom of the reservoir and ahead of the pistonwhen the piston is in its retracted position, and-means forming a groovein one of the cooperating threaded portions of the cylinder andreservoir casing for placing the bottom of the reservoir casing incommunication with the cylinder opening.

2. In a vertically positioned master cylinder device, a support, avertical cylinder, a piston reciprocable therein, a reservoir casingsecured to the cylinder, a shaft mounted on the support, a-pedal mountedon the shaft, a piston rod connected to the pedal and operativelyconnected to the piston, means carried by the reservoir casing forsuspending the reservoir from the shaft,

-a piston rod connected to the pedal and opera-' tively connected to thepiston, means carried by the reservoir casing for suspending thereservoir from the shaft, means'for connecting another portion ofthereservoir casing to the support whereby the reservoir and cylinder areprevented from turning about the shaft when the piston is actuated bythe pedal, and cooperating means carried by the pedal and the reservoircasing and providing a stop for the pedal.

'4. In a master cylinder devicefor fluid pressure brakes, a cylinder, a.piston therein, a piston rod, means for actuating the piston rod, animperforate boot having one end sealed to the piston rod and the otherend sealed to the cylinder, and means for permitting air to circulatepiston rod, said means comprising a cross-pas sage in the piston'rodwithin the interior'of the boot and a longitudinal passage in the pistonrod communicating at one end with the-cross-passage and at its other endwith the atmosphere at a protected point between the piston rod and theactuating means therefor.

5. In a master cylinder device forfluidp'ressure brakes, a verticallypositioned cylinder, a piston reciprocable therein, a piston rod,a brakepedal above the outer end of the piston rod, means for connecting theend ofthe piston rod to the pedal, an imperforate boot having one endsealed to the piston. rod and the other end sealed to the cylinder,means for permitting air to circulate in and out of the boot duringactuation of the piston, said means comprising a passage in the pistonrod placing the interior or the boot in communication with theatmosphere at a point beneath the brake pedal.

6. In a master cylinder device, a reservoir casing provided with athreaded opening, a separable cylinder provided with an annular flangeand a threaded portion adjacent thereto, one end of said cylinderextending into the reservoir casing and the threaded portion cooperatingwith the threaded reservoir opening to clamp the annular flange influid-tight engagement with the external wall of the reservoir casing, apiston reciprocable in the cylinder, said cylinder being provided withan opening in its wall at a point without the interior surface of thewall of the reservoir casing and ahead of the piston when the piston isin retracted position, and means forming a groove in one of thecooperating threaded portions of the cylinder and reservoir casing forplacing the interior of the reservoir casing in commimication with thecylinder opening.

'7. In a master cylinder device, a reservoir casing provided with anopening, a separable cyl- 5 means for clamping the flange in fluid-tighten- 10 gagement with the casing, a piston reciprocable in the cylinder,said cylinder being provided with an opening in its wall at a pointwithout the interior surface of the wall of the reservoir casing andahead of the piston when the piston is in retracted position, and meansforming a groove in one of the adjacent cooperating surfaces of thecylinder and the casing opening for placing theinterior of the reservoircasing in communication with the cylinder opening. I 1

STEVE SCHNEIL.

